This invention relates to a plastics aerosol container.
Aerosol containers are mostly made of metal, e.g. aluminium or steel (tin plate). The invention relates especially to aerosol containers made of plastics, particularly thermoplastic materials, particularly of a polyacetal (acetal resin), such as acetal homopolymer or acetal copolymer e.g. polyoxymethylene with melt flow index range 9.0 to 27.00 g/10 minutes), of a thermoplastic polyester, such as polyethylene terephthalate or polybutylene terephthalate, or a thermoplastic polyolefin, such as polypropylene.
Succesful experiments have been made by the applicants with containers made of an acetal copolymer, namely that sold under the trade name Kematal, particularly Kematal M270 and Kematal M90, and Hostaform, particularly Hostaform 13031.
The invention arose in an attempt to devise a top of a plastics aerosol container that has all the necessary properties expected from such a top, in particular good lateral impact strength, which is dependent not only on the material used and its thickness (which need not be uniform) but quite significantly on its shape. Important is also creep resistance which is dependent upon the polymer type, time, temperature, internal pressure, the geometric shape and wall thickness.
Persons skilled in the art know that a number of characteristics of plastics materials, such as chemical resistance, permeation, creep and impact strength, are fundamentally different from those of metals and, in fact, differ widely even between metals, such as aluminium and steel. Experience acquired from the testing and use of metal containers is therefore practically of no help with plastics, the characteristics of which differ from each other even more widely than is the case with metals. The basic requirements as regards non-refillable plastics aerosol containers are set out in British Standard BS 5597 published in 1978, a new edition of which relating specifically to plastics aerosols, is in preparation, which may be circular or non-circular in cross-section.